Method and system for hovering control of unmanned aerial vehicle in tunnel

Abstract

The embodiment of this present disclosure provides a control method of unmanned aerial vehicle (UAV) hovering in tunnel, which comprises the following steps: acquiring hovering information of hovering position of UAV; acquiring the position information of the current position of the UAV; determining flight parameters based on hovering information and position information. The flight parameters are used to control the UAV to move from the current position to the hovering position.

What is claimed is: 
     
         1 . A method for hovering control of an unmanned aerial vehicle (UAV) in a tunnel, comprising:
 acquiring hovering information of a hovering position of the UAV;   acquiring position information of a current position of the UAV; and   determining flight parameters based on the hovering information and the position information, wherein the flight parameters are used to control the UAV to move from the current position to the hovering position, wherein   the UAV comprises a controller, a horizontal lidar, a to-ground laser ranging sensor, a to-air laser ranging sensor, an inertial measurement unit (IMU), and a barometer, wherein   the acquiring the hovering information includes:
 acquiring the hovering information based on measurement data obtained by the horizontal lidar, the to-ground laser ranging sensor, the to-air laser ranging sensor, the IMU and the barometer, the hovering information including a hovering horizontal position and a hovering height, the position information including a horizontal position, a horizontal velocity, a vertical altitude, and a vertical velocity, and 
   the acquiring the position information includes:
 fusing the measurement data of the horizontal lidar with the measurement data of the IMU by using a filtering algorithm to obtain the horizontal position and the horizontal velocity; 
 based on the horizontal velocity and a preset velocity threshold, obtaining vertical altitude data from measurement data of one of the to-ground laser ranging sensor, the to-air laser ranging sensor and the barometer, including:
 in response to the horizontal velocity is greater than or equal to the preset velocity threshold, obtaining the vertical altitude data based on the measurement data of the barometer; and 
 in response to the horizontal velocity is less than the preset velocity threshold and tunnel ground is within a measuring range of the to-ground laser ranging sensor, obtaining the vertical altitude data based on the measuring data of the to-ground laser ranging sensor; and 
 in response to the horizontal velocity is less than the preset velocity threshold, the tunnel ground is not within the measuring range of the to-ground laser ranging sensor, and a tunnel top surface is within the measuring range of the to-air laser ranging sensor, obtaining the vertical altitude data based on the measuring data of the to-air laser ranging sensor; and 
 in response to the horizontal velocity is less than the preset velocity threshold, and the tunnel ground and the tunnel top surface are not within the measurement range of the to-ground laser ranging sensor and the to-air laser ranging sensor, obtaining the vertical altitude data based on the measurement data of the barometer; 
 fusing the vertical altitude data with the IMU measurement data by using the filtering algorithm to obtain the vertical altitude and the vertical velocity; 
 determining flight parameters based on the hovering information and the position information comprises: 
 obtaining a first flight parameter based on the hovering horizontal position, the horizontal position and the horizontal velocity; and 
 obtaining a second flight parameter based on the hovering height, the vertical altitude and the vertical velocity; wherein the controller controls the UAV to move from the current position to the hovering position based on the first flight parameter and the second flight parameter. 
 
   
     
     
         2 . The method of  claim 1 , wherein move from the current position to the hovering position comprises determining the flight parameters through a PID control based on the current position and the position information. 
     
     
         3 . The method of  claim 2 , wherein a differential adjustment amount of the PID control is negatively correlated with a wind strength coefficient. 
     
     
         4 . The method of  claim 3 , wherein the wind strength coefficient is determined based on wind strength information at a plurality of time points, and the wind strength information is determined based on the measurement data of the IMU. 
     
     
         5 . The method of  claim 4 , wherein the wind strength coefficient is a weighted sum of the wind strength information at the plurality of time points, and a weight corresponding to wind strength information far from a current time point is smaller. 
     
     
         6 . The method of  claim 3 , wherein the wind strength coefficient includes wind strength values and wind directions of past several time points, and the wind strength values are determined by a flight velocity and reference flight parameters of a reference UAV. 
     
     
         7 . A non-transitory computer-readable storage medium storing computer instructions, when reading the computer instructions in the storage medium, the computer executing the method according to  claim 1 . 
     
     
         8 . The method of  claim 1 , wherein fusing the measurement data of the horizontal lidar with the measurement data of the IMU by using a filtering algorithm comprises:
 fusing the measurement data of the horizontal lidar with the measurement data of the IMU by using an extended Kalman filtering algorithm.   
     
     
         9 . The method of  claim 1 , wherein fusing the vertical altitude data with the IMU measurement data by using the filtering algorithm comprises:
 fusing the vertical altitude data with the measurement data of the IMU by using an extended Kalman filtering algorithm.   
     
     
         10 . The method of  claim 1 , wherein obtaining the first flight parameter based on the hovering horizontal position, the horizontal position and the horizontal velocity comprises:
 obtaining the first flight parameter through a proportion integration differentiation (PID) cascade control based on the hovering horizontal position, the horizontal position and the horizontal velocity; the PID cascade control includes an outer loop control and an inner loop control, wherein the outer loop control is a horizontal position loop, a target horizontal velocity is obtained according to the hovering horizontal position and the horizontal position, and the inner loop control is a velocity loop, and the first flight parameter is obtained according to the target horizontal velocity and the horizontal velocity.   
     
     
         11 . The method of  claim 10 , wherein the first flight parameter is an attitude signal of a UAV body. 
     
     
         12 . The method of  claim 1 , wherein obtaining the second flight parameter based on the hovering height, the vertical altitude and the vertical velocity comprises:
 based on the hovering height, the vertical altitude and the vertical velocity, obtaining the second flight parameter through a PID cascade control; the PID cascade control includes an outer loop control and an inner loop control, wherein the outer loop control is a vertical altitude loop, a target vertical velocity is obtained according to the hovering height and the vertical altitude, and the inner loop control is a velocity loop, and the second flight parameter is obtained according to the target vertical velocity and the vertical velocity.   
     
     
         13 . The method of  claim 1 , wherein the second flight parameter is a throttle signal. 
     
     
         14 . A system for hovering control of a UAV in a tunnel, comprising:
 at least one storage medium including a set of instructions; and   at least one processor in communication with the at least one storage medium, wherein when executing the instructions, the at least one processor is configured to direct the system to perform operations including:   acquiring hovering information of a hovering position of the UAV;   acquiring position information of a current position of the UAV; and   determining flight parameters based on the hovering information and the position information, wherein the flight parameters are used to control the UAV to move from the current position to the hovering position, wherein
 the position information is determined based on a first position, and the first position is determined based on measurement data of an inertial measurement unit acquired when the UAV is at the current position; 
 the position information is determined by determining a reference area based on the first position, and determining the position information based on a vertical distance of the first position and vertical data of reference points in the reference area; wherein the vertical data of the reference points includes vertical coordinates of a tunnel top located at a tunnel top and vertical coordinates of a tunnel bottom corresponding to the reference points and a vertical distance from the tunnel top to the tunnel bottom; wherein determining the position information based on a vertical distance of the first position and vertical data of reference points in the reference area includes: 
 for each reference points, determining a distance between the tunnel top and the tunnel bottom based on the vertical data of the reference points; 
 determining a distance between the tunnel top and the tunnel bottom corresponding to the current position of the UAV based on a vertical to-ground sensor and a to-air laser ranging sensor; 
 determining an optimal reference point by determining a difference between the distance between the tunnel top and tunnel bottom corresponding to the current position of the UAV and the distance between the tunnel top and the tunnel top corresponding to each of the reference points; and 
 taking a position of the optimal reference point as the position information. 
   
     
     
         15 . The system of  claim 14 , wherein a range of the reference area is positively correlated with a horizontal distance between the first position and the hovering position. 
     
     
         16 . The system of  claim 14 , wherein the reference area refers to an area near the hovering position, and the reference area is a circular area with a certain radius with the first position as a center of a circle.